Electrical switch



April 5, 1960 J. E. IC-IELMINAKv ETAL 2,931,868

ELECTRICAL SWITCH Filed March l2, 1946 INVENTORS JOHN E. HELM/NAI( JULES H. SHE@ ATTORNEY United States Patent 2,931,863 ELECTRICAL SWITCH .lohn E. Helminak, Washington, D.C., and Jules H. Sreb, Silver Spring, Md., assignors to the United States gli America as represented by the Secretary of the Application March 12, 1946, Serial No. 653,910

6 Claims. (Cl. 20G-61.46)

The present invention relates to improvements in electrical switches, more particularly to manually-operated switches of the rotary type for use in ammunition.

An object of the invention is to provide an improved rotary electrical switch.

Another object of the invention is to provide an irnproved manually-operated, rotary, electricalA switch of extremely simple, small, light, economical and rugged construction.

A further object of the invention is to provide a manually-operated switch, for use in relation to electric firing circuits in all types of military missiles (projectiles, bombs, torpedoes, rockets, mines, depth charges, etc.), which will not only withstand the shock of being red from a gun, tube, or equivalent device andthe heavy stresses attendant on high speeds of rotation and translation, but also, in which locking members will prevent the openi g or closing of the switch under such'shock and stresses.

An additional objectl of the invention is to provide a rotary electrical switch for ammunition in which the position is unmistabably indicated on the exterior of the switch.

Another object of the invention is to provide an electrical safety switch suitable for use in military missiles having electrical detonating means for arming or disarming the iiring circuit. f

In the accompanying drawings:

Fig. l is a plan view ofthe switch. v

the switch Fig. 2 is an exploded perspective view of assembly.

Fig. 3 is a vertical cross-section on the line 3-3 of Fig. l.

Fig. 4 is a vertical cross-section on 4the line 4-4 of Fig. l.

Fig. 5 is a side view of afuze case, partly broken away, andwith a portion of the wall in longitudinal section, to show a suitable'V location of the switch as used in such devices. Y

. This switch is adaptable to a wide variety ofuses. It is particularly designed as a control device' for the electrical operating circuit of a fuze in a high explosive projectile. For this purpose, a small compact switch is necessary; one which may with facilitiy be installed in an accessible portion of the fuze case and provided with reliable safety means for indicating the On and Oi condition of the circuit, thus giving warning of the armed or unarmed condition of the fuze.V In carrying out the invention, a minimum number of parts are employed to insure a reliable and rugged construction and to impart simplicity in operation to the device.

Throughout the drawings the switch is shown in the closed positionto avoid any confusion.

Basically, the switch consists of a housing 11 and a rotor 12. The housing 11, which is nominally the stationary member of the switch, with respect to which the rotor turns, is shown here as an externally-threaded bushing made from any suitable electricity-conducting ma# terial such as brass. nular flange 13 for supporting, guiding and retaining the rotor 12. Spring contact arms 14 are L-shaped and the legs 15 thereof are soldered or brazed into sockets on the opposite sides of housing 11. The housing has slots 16 to accommodate the spring contacts, the slots being deeper at the free ends of the contacts. By making the bend in these L-shaped spring contacts 14 somewhat less than 90 degrees and deepening slots 16 at the free ends of the contacts, the spring contacts bear positively against the movable tab contacts 17 to be described later, thereby assuring good contact. v

The rotor 12 consists of two annular, insulating washers 18 and 19 bound together by a tubular, open-ended rivet 20 of brass or other good conducting material. Lower washer 19 is provided with a diametrical groove 21 and also with a rabbet 22 which fits against the internal ange 13 of the housing 11. The upper washer 18 is provided with a complementary, diametrical tongue 23 on its lower side which lits into the groove 21 of lower washer 19 when the rotor 12 is asembled. The tongue and groove assembly prevents any relative turning movement between the upper and lower washers by interlocking them.

inasmuch as upper washer 18 bears on the upper face of internal flange 13 and lower washer 19 bears on the lower face of this flange, when fastened together by the rivet 20 the washers retain the rotor within the housing and prevent dislocation by centrifugal or other forces. On its lower end the rivet 20 is fashioned with flat, tab contacts 17 which extend radially from the rivet and are fitted into shallow recesses in the under side of lower g washer 19. These tab contacts 17 constitute the movable Vcontacts of the switch, and when turned to the closed lead 24 is soldered or brazed to the interior of the rivet Y 24). The circuit through the switch 10 is as follows: current entering through the lead 24 ows through rivet 20 into the tab contacts 17, and from there into the two spring contacts 14 when the switch is closed, and thence to the housing lwhich is grounded. This grounding is accomplished by the contact of the external threads of the housing with the body into which it has been screwed.

The housing V11 is slotted radially at 25 and the upper washer at 26. When washer slot 26is alined with the housing slots 25 as shown in Fig. '1, a slot is formed which extends through the top of rivet 20 and completely across the switch. These slots have several functions. When alined they indicate that the switch is closed or in the On position. Housing slots 25 also permit the insertion of the switch into a body by means of a Spanner wrench; however, if washer slot 26 is alined with slots 25, a broad-bladed screwdriver mayV be used instead. The switch 10 is turned On (closed) or t0 the Oi (open) position by means of a smaller screwdriver or any other suitable tool engaging washer slot 26 alone. Releasable safety detent 27 serves as a locking means for the switch by engaging peripheral notch 28 of washer 18 in the On and the end of washer slot 26 in the O position. This detent is fashioned of spring wire and lies in a recess 29 of housing 11. The opposite end of detent 27 is anchored to the housing 11 by any suitable means, such as a tangentially-directed hole or socket or soldering or brazing.

Limit stops .to restrain the movement of rotor 12 to proper limits are provided by the ends of arcuate Way 30 in the upper washer 1S and the stop 31 mounted on the housing 11. This stop may be attached to the housing by any suitable means; as shown in Fig. 3, it consists of a piece of wire fitted into a socket in the internal Patented Apr. 5, 1960V It is provided with an internal annecessary to sh lead 24 through the tubular rivet ZtlV and solder or braze it to the interior of this rivet.

A particular application of this switch is to short out the tiring circuit of the electrical detonator or primer in order to maintain the projectile in an unarmed condition when so desired for safe handling. Then in the event of any accidental leakage of current into the liring circuit, this current would be short-circuited through lead 24, rivet 20, tab contacts 17, spring contacts 14,A and housing 11 to fuse case 32 instead of tiring the primer.

Switch housing 11 is shown as a bushing; bu-t this is merely one application and various other types of housings can be used as the occasion demands,

The operation of the switch, shown in Fig. 1 in the closed or On position, requires only the insertion of a screwdriver blade into the washer slot 26 and a counterclockwise turn of 90 degrees. yThe force of turning will disengage detent 27 from the peripheral notch 28, and at the end of the turn Ithis detent Willthen engage the end of washerslot 26. The righthand end of arcuate way 30 will by then have reached stop 31 and will prevent any further turning in that direction. This, of course, -turns the rotor assembly of the ytwo washers and the rivet thereby displacing the tab contacts 90 degrees, sliding them away from spring contacts 14; the movement of tab contacts 17 away from the spring contacts 14 breaks the circuit. The switch is now in the open or Off position which will be indicated by washer slot 26 being out of al-inement with housing slots 2S. To -turn the switch to the On position, it is only necessary to reverse the above process by turning the rotor 90 degrees clockwise. The alinement of the washer slots with the housing slots indicates that the switch is closed on On.

From the manner of mounting the switch 10k in fuze case 32 it is obvious that rotation at high speeds will not derange contacts or components ofthe switch in any manner; as spring contacts 14 will be retained within the notches 16, tab contacts 17 will remain anchored in the recesses in lower washer 18, and the rotor will beretained by the internal tiange 13'of the housing 11 and prevented from rotating by the detent 27.

While the preferred` embodiment of the invention has been described herein, the device is obviously capable of a wide variety of adaptions and applications where a rugged, economical, simple s-Witchof the locking, rotary type is desired.

We claim:

1. In an electrical switch including a housing having a pair of spaced spring arms forming stationary contacts, the combination of a rotor and coacting retaining means on the rotor and housing, a tubular open-end rivet mounted in theA rotor, and a pair of contact arms integral with the rivet for frictional engagement with said spring arms.

2. An electrical switch adapted for mounting in a pro- -ectile subjected to centrifugal forces comprising, a housing having a pair of spacedspring arms forming stationary contacts, a rotor forced of insulating material positioned in said housing, resilient retaining means releasably securing the rotor in the housing against rotation, al tubularrivet mounted in said rotor, a pair of contact arms integralwith the rivet and making frictional engagement with said spring arms in one position of said rotor, and means for limiting the rotor against accidental displacement caused by the effects of centrifugal force.

3. An electrical switch for use in a projectile subjected to centrifugal forces comprising, an externallythreaded housing having a bore and ange therein, a rotor of non-conducting material rotatably mounted in said borel and having an annular groove coacting with said flange to effectively retain said rotor in the housing against accidental displacement caused by the effects of centrifugal force, spaced spring contacts on said housing, an open-ended tubular rivet mounted in said rotor, a pair of contact arms integral with the rivet and makiugfrictional engagement with said spring contacts in one position of said rotor, coacting stop means on said housing and rotorV for limitingthe relative rotation thereof, resilient means for releasably securing the rotor in either of two possible positions within the housing, and means on the exterior of said rotor for indicating and controlling the position of the said contact arms relative to the said spring contacts.

4. An electrical switch including a housing, a resilient conducting arm mounted in the housing and constituting a relatively stationary contact, a sectional rotor rotatably mounted in the housing, `means connecting the sections of the rotor to each other, said housing having a flange, said flange and means coacting for retaining the rotor -in the housing, and a contact carried by said means and movable therewith, upon rotation of the rotor, into and out of engagement with the stationary contact.

5. An Velectricalswitch as recited in claim 4, whereinA said means is constituted by a rivet.

6. An electrical switch as recited in claim 4, wherein said rotor is formedwith a slot, and including a detent carried by the housingand -engageable in the slot.

References Cited lin the file of this patent UNITED STATES PATENTS 1,467,947 Norviell Sept. 11, 1923 1,695,957 Gernsback Dec. 18, 1928 1,809,368 Winning c June 9, 1931 2,210,842A Schellenger Aug. 6, 1940 FOREIGN PATENTS 111,258 Great Britain Nov. 22, 1917 

